The critical importance of thermal expansion

For the specification and installation of all pipework, thermal expansion must be considered. Defined simply as 'the general increase in the volume of a material as its temperature is increased' thermal expansion can, if not managed, cause pipes to leak,

As a provider to the M&E sector, questions around thermal expansion often crop up. For those specifying and installing pipework, thermal expansion is an issue that must be managed. In order to gain a deeper understanding of this topic we caught up with Dan Baker from Stourflex, a leading supplier of pipework expansion joints and pipeline equipment as part of our podcast series.

After listening to the podcast you will have an overview of:

• What is thermal expansion?

• How can you control thermal expansion?

• Why do some contractors blame expansion bellows for pipe failure?

• At what stage of an M&E project should expansion thermal products be involved?

• What advice would you give to a contractor on a project regarding thermal expansion?

What is thermal expansion?

As Dan explains: "thermal expansion in Lehman's terms is how a material reacts in a change of temperature so when you heat a piece of steel how far it grows over its length. For example in our industry, steel pipe will be at a low temperature at water situation and will, once heated up, over a 30 metre length will expand 30mm for example”

How can we control thermal expansion?

As Dan states "If you do not try to mitigate thermal expansion then it is hard to know whether or not the pipe will burst from the movement. For instance, if a pipe elbow grows in length, as soon as you install it you are likely to get leaks. When I look at thermal expansion, we look at the whole pipe system, examine how much it is growing by over its length, and look at the best ways to control that expansion". It is typically an issue for low temperature at water systems, steam systems, and chilled systems, which can cause an issue over a bigger period of time.

Is it the same for all types of pipe?

No. We are looking for the temperature of the pipe material, that is what dictates thermal expansion. For example, a 15mm copper pipe will expand the same as a 150mm copper pipe.

What is the best way to mitigate the risk of thermal expansion?

There are numerous different ways to mitigate the risk of thermal expansion. The first is through the natural flexibility of pipework, the other way is by adding expansion bellows into the pipework system.

Is Pipework installation the main cause of failure?

In most cases, yes it is. For instance, if we have installed expansion bellows into the pipework but they have not been adequately supported then the expansion bellow can fail under the weight of the pipe. This is outside of our control as a supplier. We can carry out load checks and specify the anchors that should be used, but if it has been installed incorrectly, then we are not liable.

Can early engagement help resolve installation issues?

Early and continued engagement is recommended to resolve the majority of issues. The sooner a conversation starts between the entire supply chain the more time to resolve installation issues. For us, as a supplier, we recommend that the consultant starts the conversation around thermal expansion and outlines with the specification the importance of mitigating the risk of thermal expansion. Once the specification is taken on by the contractor, it must be their responsibility to ensure that the pipework system is installed correctly with expansion joints and associated supporting anchors/fixings where required.

What advice would you give to a contractor on a project regarding thermal expansion?

Communication and early engagement are critical to the success of mitigating the risk of thermal expansion for pipe runs. Here are four points to consider:

• Early dialogue with project consultants to raise awareness around the importance of thermal expansion and the need to add natural flexibility at the design stage of pipe systems.

• The importance of supporting anchors and fixings.

• To encourage contractors to collaborate with qualified consultants in the industry.

• Keep communication free-flowing throughout a project’s lifecycle.

What is the future for expansion joints and bellows?

Within the industry, there is an increasing awareness around thermal expansion and a clear idea of how to control it. The growth in modular core risers has led to a greater need to understand how thermal expansion can have an impact on pipework systems. This comes from an increased focus on the protection of branches, low temperature, and hot water pipe runs in risers. Companies like Stourflex are investing in R&D to bring about innovations that will solve more problems created by thermal expansion.